Process for producing pig iron

Abstract

A process for producing pig iron is described involving the use of a reduction shaft furnace 1 and a melt-down gasifier 2. The sponge iron produced from iron ore in the reduction shaft furnace is fed into the melt-down gasifier and converted into a pig iron melt. The gas produced in the melt-down gasifier is passed as reducing gas into the reduction shaft furnace both via a cyclone separator 11 and a line 12 and directly via a line 13. The top gas leaving the reduction shaft furnace, after passing through a scrubber 4, is largely returned via a CO 2 scrubber 6, in which CO 2 and H 2 O are removed from the gas, in such a way that it can be used for forming the reducing gas in the melt-down gasifier and also as a cooling gas for the reducing gas produced in said gasifier.

I claim: 
     
       1. In a process for producing pig iron in which iron ore is reduced in a reduction shaft furnace issuing a top gas containing CO 2  and a sponge iron obtained as a result thereof is subsequently passed through a fluidized bed formed within a melt-down gasifier above an O 2  tuyere, a gas and a carbon carrier being introduced into said melt-down gasifier, and a reducing gas produced in said melt-down gasifier being introduced as the  reducing gas into said reduction shaft furnace; the improvement comprising the steps of compressing and at least partially scrubbing the CO 2  from the top gas issuing from said reduction shaft furnace, and then introducing at least a portion of this scrubbed and compressed top gas into the melt-down gasifier at about half the height of said fluidized bed. 
     
     
       2. The process of claim 1 wherein the scrubbed and compressed top gas introduced into the melt-down gasifier at about half the height of said fluidized bed is preheated to a temperature of between about 300° C. to about 600° C. prior to said introduction. 
     
     
       3. The process of claim 1 wherein the temperature of the gas upon preheating is about 400° C. 
     
     
       4. The process of claim 1 wherein an additional portion of the scrubbed and compressed top gas is introduced into the melt-down gasifier at the level of the O 2  tuyer. 
     
     
       5. The process of claim 4 wherein a second additional portion of the scrubbed and compressed top gas is introduced as a cooling gas into the stream of reducing gas passing into the reduction shaft furnace. 
     
     
       6. The process of claim 5 wherein the amount of the second additional portion of the scrubbed and compressed top gas is such as will cool said stream of reducing gas passing into the reduction shaft furnace to a temperature of about 850°